This is a multicenter randomized double blind placebo controlled trial to assess the effectiveness of LJP394 in pts. w/lupus kidney disease. The primary objective of study is to determine whether LJP394 is effective in preventing renal flare in patients with a history of lupus kidney disease. Some other objectives include is LJP394 effective in the reduction of anti-dsDNA antibodies reducing signs and symptoms of active SLE, determining whether pts taking LJP394 require less treatment with cyclophosphamide and prednisone than pts w/placebo.